Convertible ladder



May 13, 1958 K. w. cousE 2,834,528

' CONVERTIBLE LADDER Filed July 12, 1954 4 Sheets-Sheet l .May 13, 1958K. w. cousE 2,834,528

CONVERTIBLE LADDER Filed July 12, 1954 4 Sheets-Sheet 2 May 13, 1958 K.w. COUSE CONVERTIBLE LADDER 4 Sheets-Sheet 3 Filed July 12, 1954 A. ll IM y 1 1958, K. w. COUSE 2,834,528

CONVERTIBLE LADDER Filed July 12, 1954 4 Sheets-Sheet 4 CONVERTIBLELADDER Kibbey W. Couse, Newark, N. J. Application July 12, 1954, SerialNo. 442,836 7 Claims. (Cl. 228-25) The invention relates to ladderconstructions and more particularly to new and useful improvements in aladder capable of serving as a single flight ladder and adapted to beconverted into a propped or step ladder or into an extension ladder.

In the ordinary ladder construction which is adapted to be convertedinto a step ladder or extension ladder, the ladder sections are unsureand shaky and it is necessary to provide safety grip sockets, safetycatches, guide bands and other attachments which are cumbersome, apt tobecome accidentally detached or improperly attached, are expensive andneed considerable skill to manipulate. Furthermore, in such ladderconstructions the top or last step or rung is usually much too close tothe supporting surface to permit secure foot and hand space.

A prime object of the present invention is to provide a ladder sectionwhich is complete in itself to serve as a single flight ladder but whichis provided with means for detachably connecting another identicalladder section thereto to produce a rigid step ladder or for detachablyconnecting another identical ladder section or sections thereto toproduce a rigid extension ladder.

Another object of the invention is to provide a ladder section adaptedto be associated with another identical section to produce a step ladderor an extension without the necessity of the usual attachments forsafety and guiding purposes.

A further object of the invention is to provide a ladder section adaptedto be converted into a step ladder characterized by means for producingthe proper safety angle of the supports for the step ladder.

Still another object of the invention is to provide a ladderconstruction with means for spacing the uppermost step or rung away fromthe vertical supporting surface in order to provide secure'foot and handspace.

Other objects of the invention are to provide a ladder of this characterwhich is simple in construction, characterized by fewness of parts,sturdy and rigid, readily assembled and disassembled and which can bemanufactured and sold at reasonable cost.

For further comprehension of the invention and of the objects andadvantages thereof, reference will be had to the following descriptionand accompanying drawings, and to the appended claims in which thevarious novel features of the invention are more particularly set forth.

On the accompanying drawings forming a material part of the presentdisclosure:

Figure 1 is a front elevational view of a ladder construction embodyingmy invention.

Figure 2 is a vertical sectional view taken on the plane of the line 2-2of Figure 1.

Figure 3 is a rear View thereof.

' Figure 4 is a fragmentary perspective view of the top portion of theladder construction of Figure 1, parts being broken away.

Figure 5 is a side elevational view of a two section ladder forming astep ladder embodying another form of the invention, the ladder beingshown in dotted lines in nited States Patent 0 2,834,528 Patented May13, 1958 2 inoperative collapsed condition, and parts being shown insection.

Figure 6 is an enlarged fragmentary side elevational view showing thetop of the ladder of Figure 5, parts being broken away.

Figure 7 is a plan view looking from the top along the line 7--7 ofFigure 5.

Figure 8 is an enlarged fragmentary side elevational view of the top ofthe side rails of the ladder of Figure 5, showing the first step inassembling the step ladder sections, parts being broken away.

Figures 9, 10 and 11 are fragmentary edge views of the ladder of Figure14, showing steps in the assembling of the ladder sections, parts beingbroken away;

Figure 12 is a fragmentary edge view showing an overlapped joint betweentwo adjacent ladder sections of the ladder of Figure 14, parts beingbroken away;

Figure 13 is an enlarged fragmentary front elevational view of a jointbetween two adjacent ladder sections of the ladder of Figure 14, partsbeing broken away;

Figure 14 is a front elevational view of a three section ladder formingan extension ladder embodying another form of my invention.

Figure 15 is an edge view thereof, showing in dot-dash lines the lowerpart of another ladder section in initial assembling position.

Figure 16 is an edge view of the ladder of Figure 14 shown in operativeposition against a supporting structure.

Figure 17 is a similar view of a single ladder section shown hooked overa support.

Referring in detail to the various views of the drawings andparticularly to Figure 1, a ladder section made in accordance with thepresent invention is designated 1 and comprises two elongated stiles orside rails 2 and 3 having slanting steps or rungs 4 secured to andbridging the stiles or rails at regular intervals. The stiles or railsare formed of metal and are tubular in formation and square incross-section, each stile including a front wall 5, a rear wall 6 andside walls 7. The steps 4 are formed of inverted channel-shaped metalbars fastened to the inner side walls 7 of the stiles by welding or inany other suitable manner.

According to the present invention, the ladder section 1 is providedwith means for combining two such sections in order to produce either astep ladder 8 such as shown in Fi ure 5 or combiningtwo or more of suchsections to produce an extension ladder 9 as shown in Figure 9. Suchmeans includes a curved hook-like extension 10 projecting from the topend of stile or rail 2 and a curved hook-like extension 11 projectingfrom the top end of stile or rail 3. Extension 10 is in the form of anelongated metal tube having a straight portion 12 projecting into thetop end of the rail 2 and a curved end portion 13 projecting outwardlyof said top end. A squareshaped plate l4is sleeved over the straightportion 12 of the tube and welded to said portion adjacent its innerend. The plate is secured to the stile or rail 2 along its peripheraledge by welding or the like. A similar shaped plate 15 is similarlymounted and secured to the tube at the outer end of its straight portion12 and is welded to the top end edge of the stile. The plates 14 and 15hold the tube against twisting or bending in the side rail and plate 15in addition serves as a closure for the top end of the side rail.

The extension 11 is similar in shape to the extension 10 with a straightportion 16 and a curved end portion 17 projecting outwardly of the stileor side rail 3 but is formed of solid metal rod. The extension 11 isarranged and secured to the stile or side rail 3 by means of plates 18and 19 similar to the plates 14 and 15, respectively.

extension 10. A semi-cylindrical enlargement- 20 is formed on the outerconvex surface of the curved portion 17 and extends from the closureplate 19 outwardly a considerable distance forming a shoulder 21 at itsouter end.

The stile or side rail 2 is also formed with an elongated slot 22 in itsfront wall 5 and with an elongated slot.23 in its rear wall 6 in linewith the slot 22, the slots 22 and 23 being sufliciently wide to receivethe curved portion 13 of the extension 10. Side rail 3 is also formedwith an elongated slot 24 in its front wall 5 opposite the slot 22 andwith an aligned slot 25 in its rear wall 6, said slots beingsufliciently wide to receive the curved portion 17 of the extension 11.The slots are positioned a suitable distance above the bottom ends ofthe stiles or side rails in order to provide ample overlapping space forthe side rails. The uppermost step 4 is spaced an equal distance fromthe tops of the extensions 10 and 11 and is formed with an extensionwhich curves outwardly and upwardly to form a substantially V-shapedsocket portion 26 extending the length of the step.

In order to produce a step ladder, such as the ladder 8 shown in Figure5, two ladder sections 1 are associated or combined. This isaccomplished by positioning the rear walls 6 of the stiles of thesections in opposed relation and inserting the solid curved rod portions17 of the extensions 11 into the tubular curved portions 13 of theextensions 10 as shown in Figures 5 and 6. The inward movement of thecurved rods 1'7 into the tubular curved portions 13 is limited by theshoulders 21 of theenlargements 29 engaging the end edges of the tubularcurved portions as shown in Figure 6. When the curved portions of theextensions are thus in telescopic engagement, the ladder sections 1 willbe fanned outwardly as shown in Figure 5 to a degree preferably 30 fromthe vertical. In order to prevent the ladder sections from spreadingbeyond the safety angle, the angle of the shoulder 21 on the enlargementis fixed at 30 from the vertical as shown in Figures 5 and 6.

In order to provide the preferred 30 angle, the extension members ltland 11 must be properly curved and to produce the proper arc thefollowing method has been found satisfactory in practice. A normallystraight length of tubular stock and a normally straight length of solidrod stock are bent at their centers into semi-circles. In order todetermine the proper size of the semi-circles, a dimension approximatingslightly more than four times the side width of a stile or side wall ofthe ladder section is taken as a center line diameter. The tubular stockand the rod stock are then cut so that each is equal to one-quarter of acomplete circle. The original lengths of both the tube stock and rodstock must be such as to leave a proper length when bent and cut so asto allow a straight portion sufiiciently long to be inserted into thetop end of the side rail and supported therein. When thus dimensionedand the side rails 2 and 3 are placed vertically with their rear wallsopposed as shown in Figure 8 and with their longitudinal axes in linewith the axes of the tubes and rods, the outer end edges of the tubesand rods will abut each other, end to end, the end of one rod abuttingthe end of its adjacent receiving tube.

It will be seen that when two ladder sections 1 are thus associated orcombined a step ladder is produced which needs no spread struts, safetycatches or extra attachments of any kind, and which is sturdy, rigid,safe and portable. The step ladder may be almost completely folded andstill retain its identity as a step ladder.

In order to produce an extension ladder, a ladder section 1 is used as amain or bottom section and another ladder section 1 or a plurality ofsuch sections 1 are telescopically mounted on the main or bottom sectionand on each other. In the extension ladder illustrated in Figure 14, oneladder section 1 serves as a main or bottom section A and two suchladder sections serve as intermediate and upper auxiliary laddersectionsB and l C, respectively. In assembling the ladder sections, theintermediate auxiliary section B is positioned so that the front wallsof its side rails face the rear walls of the side rails of the main orbottom section A. The front flange or wall of the lowermost invertedchannel-shaped step 4 of the intermediate auxiliary section B isinserted into the V-shaped socket portion 26 formed on the uppermoststep 4 of the main or bottom ladder section A as viewed in Figures 9, 10and 11 so that the curved extensions 10 and 11 or the main or bottomsection A will point toward the front walls of the side rails of theintermediate auxiliary section B whereby when the side rails of the mainand auxiliary sections are brought into contacting relation, theextensions 10 and 11 on the bottom section A will be in alignment withthe slots in the auxiliary sectionB. The section B is then swung towardthe main section A using the V-shaped socket portion 26 as a fulcrumuntil it is in telescopic alignment with the main section. Theextensions 10 and 11 of the main section A will then pass through theslots 22 and 24 in the front walls 5 and through the slots 23 and 25 inthe rear walls 6 of the auxiliary section B. When completely inserted,the free ends of the extensions 1t) and 11 protrude slightly beyond theouter surface of the rear walls 6 of the side rails of the auxiliarysection B. Cotter pins 27 extending through openings 28 formed in theprotruding outer ends of the extensions 10 and 11'prevent withdrawal ofthe extensions and lock the main and auxiliary sections rigidly togetheras a unit. The diameters of the slots 23 and 25 in the rear Walls 6 ofthe side rails through which the extensions 1% and 11 pass are onlyslightly larger than the diameters of the extensions 10 and 11 and lessin diameter than the depth of the groove forming the socket portion 26.

This prevents unseating or displacement of the front flange of the step4 of the auxiliary section B in the socket portion 26 of the mainsection A and furthermore prevents accidental swinging of the main andauxiliary ladder sections away from each other.

The upper auxiliary ladder section C of the extension ladder 9 issimilarly combined and associated with the intermediate auxiliarysection B by similarly inserting the front flange or wall of thelowermost step 4 of said upper auxiliary section C into the V-shapedsocket portion 26 of the intermediate auxiliary section B and swingingthe extensions 10 and 11 of the section B through the slots in the wallsof the side rails of the upper section C and rigidly fastening thesections together by the cotter pins 27.

If desired, the cotter pins 27 may be suspended from a flexible chain orthe like attached to the adjacent side rail of the ladder section.

While three ladder sections 1 have been shown assembled to produce theextension ladder 9, it will be understood that any number of laddersections 1 may be used to provide an extension ladder of the desiredlength, and the side rails of the ladder sections may. be of unequallength if desired.

The extension ladder thus described is rigid and safe and needs none ofthe usual grip sockets, safety catches and guide bands.

In using the extension ladder, the extensions 10 and 11 may be hookedover a support 29 as shown in Figure 17, or their free outer ends mayrest against a vertical support such as indicated at 30 in Figure 16thereby spacing the upper end of the ladder away from such support andthus provide ample foot and hand space for the user.

Anti-skid devices may be mounted on the bottom ends of the stiles orside rails of the ladder section 1- if desired.

The solid rod extension 11 of ladder section 1 may be provided with apointed tip which will permit the ladder construction to be used inAlpine work or scaling walls. The improved ladder construction may alsobe used in bridging crevasses and the like. Furthermore,

the curved extensions and 11 may be formed with additional openings,adjacent their free outer ends to accommodate additional cotter pins asa safety feature.

While I have illustrated and described the preferred embodiments of myinvention, it is to be understood that I do not limit myself to theprecise constructions herein disclosed and the right is reserved to allchanges and modifications coming within the scope of the invention asdefined in the appended claims.

What I claim is:

1. A ladder convertible to provide a propped ladder or an extensionladder and comprising a main ladder section and an auxiliary laddersection, each section including side rails having steps secured theretoand bridging the same, curved extensions on the top ends of the siderails of the main section, curved extensions on the top ends of the siderails of the auxiliary section separably telescopically connectible tothe curved extensions on the main section for use of the ladder as apropped ladder, the side rails of said auxiliary section adjacent theirbottom ends having slots, the curved extensions of said main sectionbeing separably receivable in said slots when the ladder is used as anextension ladder, and means to secure the side rails of the laddersections together when the ladder is used as an extension ladderincluding means carried by the curved extensions of the main section andcoactive with said auxiliary section, and a part on a step of one ofsaid main and auxiliary ladder sections cooperative with a part on astep of the other of said main and auxiliary ladder sections.

2. A ladder section for a convertible ladder comprising side railshaving slots therethrough, steps bridging said rails at spacedintervals, at least one of said steps having a flange along one edge,curved extensions each on one rail at one end of the ladder section andseparably insertable into one of said slots of a similar ladder section,one of said curved extensions being tubular to serve as a socket for theother extension of a similar ladder section, and an upwardly facinggrooved extension on one step to receive said flange of a similar laddersection, whereby both said curved extensions and said flange of saidladder section may be inserted into said slots and said groovedextension respectively of another ladder section to provide an elongatedstraight ladder, and the second-mentioned extension of said laddersection may be inserted into the first-mentioned extension of a similarladder section to provide a short step ladder.

3. A ladder section as defined in claim 2 with the addition of a stop onthe first mentioned curved extension of said ladder section to abut theend of the secondmentioned curved extension on a similar ladder sectionto limit movement of the ladder sections apart.

4. A convertible ladder comprising two ladder sections each includingside rails having slots therethrough and steps bridging said rails atspaced intervals longitudinally of the rails, at least one of whichsteps has a depending flange, curved extensions on the rails at one endof one of said sections each separably insertible into one of said slotsin the other section, one of said curved extensions being tubular toserve as a socket for the other extension of the other ladder section,and an upwardly facing grooved extension on one step to receive saidflange on the step of the other ladder extension, whereby both saidextensions and said flange of one ladder section may be inserted intosaid slots and said grooved extension respectively of the other laddersection to provide an elongated straight ladder or the secondmentionedextension of each ladder section may be inserted into thefirst-mentioned curved extension of the other ladder section to providea short propped ladder.

5. A convertible ladder as defined in claim 4 wherein thesecond-mentioned curved extension of each ladder section has anenlargement to abut the end of the tubular curved extension of the otherladder section and serve as a stop when the second-mentioned curvedextension is inserted into the tubular curved extension.

6. A convertible ladder as defined in claim 4 with the addition of meansseparably connectible to the outer ends of the curved extensions of oneladder section to coact with the rails of the other ladder section toprevent pivotal movement of said ladder section about said flange andsaid grooved extension when the ladder sections are arranged to providean elongated ladder.

7. A ladder section for a convertible ladder comprising side railshaving slots therethrough, steps bridging said rails at spacedintervals, said section having a downwardly extending flange, curvedextensions each on one rail at one end of the ladder section andseparably insertable into one of said slots of a similar ladder section,one of said curved extensions being tubular to serve as a socket for theother extension of a similar ladder section, and an upwardly facinggrooved extension to receive said flange of a similar ladder section,whereby both said curved extensions and said flange of said laddersection may be inserted into said slots and said grooved extensionrespectively of another ladder section to provide an elongated straightladder, and the secondmentioned extension of said ladder section may beinserted into the first-mentioned extension of a similar laddersectionto provide a short step ladder.

References Cited in the file of this patent, UNITED STATES PATENTS68,836 Boyd Sept. 17, 1867 482,402 Booth Sept. 13, 1892 518,961 Lang May1, 1894 572,201 Hausmann Dec. 1, 1896 575,759 Perkins Jan. 26, 1897672,945 Kloepfer Apr. 30, 1901 1,299,784 Sabo Apr. 8, 1919 1,467,245Anlauf Sept. 4, 1923 2,129,401 Botinger et al Sept. 6, 1938 FOREIGNPATENTS 23,512 Germany Mar. 14, 1901 48,087 Germany -l Oct. 6, 1888312,677 Great Britain May 30, 1929

